[Nek5000-users] About the iobj in the drag calculation

[nek5000-users at lists.mcs.anl.gov]

These are just rescalings of turbulent fluctuations
in terms of wall units, which allows them to be compared with
other data in the literature.



On Thu, 29 May 2014, nek5000-users at lists.mcs.anl.gov wrote:

> Hi,
     I'm sorry to trouble. I find these lines in set_obj subroutine
             if (f.eq.1) iobj=1  ! lower wall
             if (f.eq.3) iobj=2  ! upper wall
     so this defines which wall to be represented. Another question comes that why the urms is calculate like
     do i=1,m
                 write(56,3) yy(i)+1
      &                     ,(yy(i)+1)*Re_tau
      &                     , (urms_pl(i)-(uavg_pl(i))**2)/u_tau**2
      &                     , vrms_pl(i)/u_tau**2
      &                     , wrms_pl(i)/u_tau**2
      &                     , uvms_pl(i)/u_tau**2
                 write(57,3)  yy(i) + 1.
      &                     , (yy(i)+1.)*Re_tau
      &                     , uavg_pl(i)/u_tau
     3           format(1p15e17.9)
             enddo

As can be seen,R_uu=(urms_pl(i)-(uavg_pl(i))**2)/u_tau**2, while R_vv=vrms_pl(i)/u_tau**2,why?






ÔÚ 2014-05-29 02:24:34£¬nek5000-users at lists.mcs.anl.gov дµÀ£º

Hi,all:
     I read Paul's reply in this mail https://lists.mcs.anl.gov/mailman/htdig/nek5000-users/2014-May/002756.html
     And got to know something about objects. As you say, the object is a collection of faces, here , I have a question about the iboj, how could I know which face it represent with iboj? As in turbChannel.usr,
      dragx_avg = alpha*dragx_avg + beta*0.5*(dragx(1)+dragx(2))
      I think it means to do the time-average of the average dragx on planey1 and planey2, as
      0.5*(dragx(1)+dragx(2))
  indicates, while how to calculate the dragx on the planex1, planex2, planez1 and planez2? for the maxobj in this example is only 4 and dragx is defined as
      dragx(0:maxobj)

Thank you
Xianbei




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